Jianhao Tong,Hanxin Wu,Xiaohan Jiang,Jing Wang,Jingli Pang,Haonan Zhang,Ziming Xin,Jiyan Shi
The exploration of microbial resources to reduce Pb accumulation in rice attracted great attention. In this study, we found Penicillium oxalicum SL2, a Pb-tolerant strain with good capability of dissolving phosphorus and stabilizing Pb in soil, was able to colonize on the root surface of rice seedlings without additional carbon sources, and promoted the secretion of metabolites related to amino acid metabolism , organic acid metabolism, signal transduction and other pathways in rhizosphere exudates, in which the secretion of oxalate increased by 47.7 %. However, P. oxalicum SL2 increased Fe(II) proportion and Fe availability on the root surface, resulting in iron plaque content decrease. Moreover, by converting root surface Pb from Pb-Fe state to PbC 2 O 4 and Pb-P compounds, P. oxalicum SL2 increased Pb intercept capacity of iron plaque by 118.0 %. Furthermore, P. oxalicum SL2 regulated element distribution on the root surface, and reduced the relative content of Pb on the maturation zone of root tip , which was conducive to reducing Pb uptake by apoplastic pathway and the risk of Pb accumulation in root system . Our findings further revealed the interaction between P. oxalicum SL2 and rice root, providing a theoretical basis for the development and application of microbial agents in Pb-contaminated farmland.
Peicheng Huang,Dan Zou,Chunhua Dong,Chongjian Tang,Qingzhu Li,Pengwei Zhao,Ping Zhang,Qi Liao,Zhihui Yang
Selenium (Se) fortification is witnessed to simultaneously inhibit absorbing Cadmium (Cd) and Arsenic (As) by rice plants, but the mechanism is unclear. Here, the effects of Se on the root morphology, iron plaque (IP) content, soil Fe 2+ content, radial oxygen loss (ROL), and enzyme activities of the rice plants in the soil contaminated by Cd and As were intensively investigated through the hydroponic and soil experiments. Se effectively alleviated the toxic effects of Cd and As on the plants and the dry weight, root length, and root width were increased by 203.18%, 33.41%, and 52.81%, respectively. It also elucidated that ROL was one of the key factors to elevate IP formation by Se and the specific pathways of Se enhancing ROL were identified. ROL of the plants in the experiment group treated by Se was increased 36.76%, and correspondingly IP was magnified 50.37%, compared to the groups with Cd and As. It was owing to Se significantly increased the root porosity (62.11%), facilitating O 2 transport to the roots. Additionally, Se enhanced the activities of catalase (CAT) and superoxide dismutase (SOD) to promote the catalytic degradation of ROS induced by Cd and As stress. It indirectly increased O 2 release in the rhizosphere , which benefit to form more robust IP serve as stronger barrier to Cd and As. The results of our study provide a novel molecular level insight for Se promoting root IP to block Cd and As uptake by the rice plants.
Antibiotic pollution in the environment poses stress to plants. Iron plaque on plant roots plays a vital role in inhibiting the uptake of pollutants by plants. However, the role of environmental factor-driven alterations in iron plaque on plant uptake of the pollutant remains unclear. In this study, we selected Shewanella oneidensis MR-1, renowned for its iron-reduction capabilities, to explore its influence on the formation of iron plaque and subsequent uptake and transformation of ciprofloxacin (CIP) by plants. The presence of S. oneidensis MR-1 induced significant modifications in iron plaque composition, leading to a reduction in the iron plaque amount and an increase in ferrihydrite content within iron plaque. The changes in iron plaque composition substantially enhanced CIP immobilization on the plant root surface, thereby impeding both the uptake and apical translocation of CIP, resulting in a marked reduction in CIP-induced phytotoxicity. Furthermore, iron plaque formed with the participation of S. oneidensis MR-1 accelerated the removal of CIP from solution and induced a greater generation of oxidative degradation products. This study underscores the potential of microorganisms to influence the formation of rhizosphere iron plaque and inhibit plant uptake of pollutants, providing novel insights into safe production practices and pollutant degradation strategies.
危险品化学品经营许可证（带存储）